Rev it as high as you like - but only up to the redline. Never past it. Most GM stuff built after 1995 has at least 1 rev limiter, some have 2. A rev limiter stops the engine from revving past a pre-set RPM. It doesn't hurt the engine to "bounce it" off the rev limiter. Rev limiters may work in several ways. Some cut off the fuel, some cut off the spark plugs, some do both. Some, on cars with electronic - i.e. no physical connection between your accelerator pedal and the actual throttle - may actually take control of the throttle and close it. Basically, if you have a rev limiter, you can put your foot to the floor, and the engine will not rev past it's preset limits (as long as the rev limiter, engine computer, sensors... etc. are all working as they should). The most common rev limiter is set just at, or just past redline. This rev limiter keeps people who are foolish and/or not paying attention from blowing their motor (hopefully). The second one is set lower, usually around the 4000 RPM mark. This second one is speed sensitive on my GM car. I have a GM 5 speed, and if I'm completely stopped in neutral (or any gear), and I accidentally rest my foot on the gas or something like that, it will only rev to 4000 RPMs. If I get the car rolling, even 2-3 miles per hour, I can rev it to redline. Since you mentioned "park" in your question, you probably have an automatic. And unless it's a really old trans am - it should have a rev limiter. And I agree... it's fun to rev it. Especially a nicely tuned V8. It sounds good - like a symphony... have fun. Just don't do it in front of a cop. At the very least, he'll tail you. At worst - you will get a B.S. ticket for some trumped up charge. Have fun. Rev away!!! Revving the engine does no harm. NOW... if you rev it up, and then drop it into Drive or let the clutch out very quickly... that can possibly cause harm. Usually, transmissions, clutches, drive axles...etc (all together called the drivetrain) can handle a "hard launch". But if you do it over and over and over, you'll either brake something expensive, or at least put excessive wear and tear on the engine and drivetrain. So, again, unless it's very old, you probably have a rev limiter. Either way - young or old - revving it short of redline should.... do no harm.